MICROSCOPIC STUDY OF FUNGI

Question 1

 It is used to observe clinical specimens for the presence of
fungal elements or to identify the fungus following cultur

Answer 1

Microscopy

Question 2

What is the stain of choice that we use in microscopy?

Answer 2

LACTOPHENOL
COTTON BLUE

Question 3

It is a simple cover slipped preparation
and mostly good for yeast usually or commonly used
procedure that we performed

Answer 3

Wet preparation/ Wet mount

Question 4

What objective is a wet mount observed?

Answer 4

LPO

Question 5

This dissolves keratin

Answer 5

KOH

Question 6

This dissolves keratin

Answer 6

KOH

Question 7

What prevents thr crystalization?

Answer 7

Glycerol

Question 8

spores are seen outside the hair

Answer 8

Ectothrix

Question 9

spores are inside the hair

Answer 9

Endothrix

Question 10

Gives more rapid maceration and clearing than KOH
however, preparations does not last because specimen
dissolve
. Not for hair or thin scales of skin
. Specimen may dissolve

Answer 10

Dimethyl sulfoxide (DMSO)

Question 11

This is a fluorescent dye, which binds selectively to chitin of
the fungal cell wall. The specimen then can be observed
under fluorescent microscope.

Answer 11

Calcofluor white

Question 12

This is used for encapsulated yeasts

Answer 12

India Ink/ nigrosin

Question 13

This is used for rapid staining of blood and bone marrow fungi. And is used for histoplasma capsulatum.

Answer 13

Wright’s Giemsa

Question 14

• Pink to pinkish blue
• Useful for staining tissue sections
• Common stain for tissue processing

Answer 14

H & E (HEMTOXYLIN AND EOSIN)

Question 15

• It will stain the polysaccharide in the cell wall of the
  fungi
• For the demonstration of glycogen
  and neutral mucins.
• Red/ purple against green

Answer 15

Periodic Acid Schiff

Question 16

What is the color of PAS positive material, Nuclei, PAS digest material?

Answer 16

• PAS positive material: MAGENTA
• Nuclei: BLUE
• PAS digest material: COLORLESS

Question 17

What is the mechanism of PAS?

Answer 17

Certain tissue elements are oxidized by PAS

Question 18

• For tissue section
• Black with lavender-gray areas
  because of silver precipitate
  deposits

Answer 18

METHENAMINE SILVER (MS)

Question 19

What is the mechanism of methenamine silver?

Answer 19

Chromic acid treated fungi possess aldehydes which will reduce the
hexamine-silver mixture to produce a black deposit.

Question 20

What originally contains meyer’s mucicarmine?

Answer 20

Aluminum hydroxide

Question 21

Gives more consistent results for the
detection of Cryptococcus neoformans

Answer 21

MEYER’S MUCICARMINE (MM)

Question 22

What is the color of MEYER’S MUCICARMINE (MM) under the microscope?

Answer 22

An evident rose to red with nucleus

Question 23

May be used to detect fungal antigen
in clinical material such a pus, blood,
CSF, tissue impression smears and in
paraffin sections of formalin fixed
tissue.

Answer 23

FLUORESCENT ANTIBODY STAINING

Question 24

Enumerate the method under wet preparation used in microscopic study of fungi

Answer 24

KOH
DIMETHYL SULFOXIDE (DMSO)

CALCOFLUOR WHITE
INDIA INK/ NIGROSIN
WRIGHT’S GIEMSA

Question 25

Enumerate the special stains used

Answer 25

H & E (HEMTOXYLIN AND EOSIN) PERIODIC ACID SCHIFF (PAS) METHENAMINE SILVER (MS) MEYER’S MUCICARMINE (MM) FLUORESCENT ANTIBODY STAINING

Question 26

This is the most common stain used for microscopy of fungi

Answer 26

Lactophenol Cotton Blue

Question 27

Describe lactic acid, phenol and cotton blue.

Answer 27

- Lactic acid: fixative - Phenol: fungicide - Cotton Blue: stain

Question 28

Enumerate the stains we used in examination of results

Answer 28

LACTOPHENOL COTTON BLUE (LPCB) POLYVINYL ALCOHOL (PVA-CB)

Question 29

- Very common and rapid method - Disadvantage: Distorts colonial morphology

Answer 29

Tease mount

Question 30

 Substitute for tease mount  Morphology is preserved  Cannot be preserved for long periods  The tape isn’t sterile  May cause widespread dispersion of conidia since the procedure is somewhat messy

Answer 30

Cellulose tape swab

Question 31

What would cellulose tape swab cause to widespread since it is messy?

Answer 31

Conidia

Question 32

 Needs tease-mount first (get small amount of sample from the culture)  Usually perform or done when negative to conidia  The macroscopic characteristics are observed  Used for fungi with “delicate linkages”  Between conidium and conidiophore

Answer 32

MICROSLIDE/ AGAR BLOCK

Question 33

What is the characteristic of fungi if used in MICROSLIDE/ AGAR BLOCK?

Answer 33

Delicate linkages

Question 34

MICROSLIDE/ AGAR BLOCK is usually performed if the conidia is?

Answer 34

Negative

Question 35

 More preferred than the media since it is lesser chance that the spores will be release in the environment  Less chance for dehydration and it is easier to store also

Answer 35

Germ test tube

Question 36

What is the characteristic of germ test tube?

Answer 36

Germ tube is a short outgrowth, non-septate germinating hypha.

Question 37

From what microorganism is yeast differentiated to using the germ test tube?

Answer 37

C. Albicans

Question 38

 An initial filamentous outgrowth from a conidia or spore  An asexual reproductive structure

Answer 38

Germ tube

Question 39

Enumerate the preparation of microscopic examination

Answer 39

Tease mount Cellulose tape swab Microslide agar/ block Germ test tube Germ tube

Question 40

How many drops of formaldehyde are absorbed by cotton then placed in a tube?

Answer 40

10 drops

Question 41

In sealing with parafilm, how long is the interval of culture?

Answer 41

6-12 months

Question 42

How long is the interval of mineral oil?

Answer 42

24

Question 43

How long is the interval of freezing?

Answer 43

@ –20°C to –70°C - 1 to 2 years interval

Question 44

In preserving using sterile water, how many mL of distilled water in culture?

Answer 44

2mL

Question 45

Monoclonal antibody labeled with fluorescent dyes can be used to detect several fungi in the clinical specimens. It is the most commonly used

Answer 45

Immunofluorescence

Question 46

Detection of anti-fungal antibody is helpful in diagnosis of sub-cutaneous and systemic mycoses, prognosis and response to anti-fungal drugs

Answer 46

Serology

Question 47

Enumerate the different serologic techniques

Answer 47

1. Agglutination 2. Immunodiffusion 3. Counter-immunoelectrophoresis 4. Complement fixation test 5. Immunofluorescence 6. RIA (Radioimmunoassay) 7. ELISA (Enzyme-Linked Immunosorbent Assay)